1. Field of the Invention
The present invention relates to a wireless IC device system that determines the authenticity of an article by using an RFID tag and a method therefor.
2. Description of the Related Art
Japanese Unexamined Patent Application Publication No. 2007-150642 describes a wireless tag (RFID tag) that is used for physical distribution management and/or for authenticity determination. The wireless tag of Japanese Unexamined Patent Application Publication No. 2007-150642 was developed to solve a conventional problem in that since the frequency band in which communication is possible is narrow and the frequency of a communicatable signal varies due to manufacturing variations or the surrounding environment of the wireless tag, communication failure with an interrogator (reader/writer) occurs. Consequently, the wireless tag of Japanese Unexamined Patent Application Publication No. 2007-150642 is configured such that authentication of an article is performed by changing the frequency of a signal using the interrogator to find a frequency at which communication is possible.
FIG. 1 is a block diagram illustrating a configuration of a control logic circuit 110 in the interrogator.
The control logic circuit 110 includes a PLL control section 301, a transmission signal generation section 302, a reception signal processing section 303, a transmission and reception control section 304, a storage section (hopping channel-wireless tag ID storage table) 305, and an external interface section 306.
The storage section 305 stores the relationship between a wireless tag ID and a frequency changing channel (carrier frequency) to which the wireless tag responds. The PLL control section 301 controls carrier frequencies.
Meanwhile, Japanese Unexamined Patent Application Publication No. 2005-345802 discloses a configuration that includes an electronic equipment main body (camera) and a removable unit. The unit is provided with an information communication chip that stores identification information and other information, and an antenna. The electronic equipment main body (camera) includes an antenna and a device arranged to read information, and further includes a controller arranged to control operations with the unit based on read information.
RFID tags are normally provided on articles to determine authenticity. However, data written in an RFID tag can be read by analyzing the inside of the RFID tag, and thus, duplication of the RFID is technically possible. Even when the system described in Japanese Unexamined Patent Application Publication No. 2007-150642 is used, the authentication process is performed using only a certain frequency in a frequency band in which communication is possible. Consequently, when a counterfeit wireless tag having the same identification code is attached to an article, the article is falsely determined to be authentic.
Further, in the wireless tag system described in Japanese Unexamined Patent Application Publication No. 2007-150642, when a wireless tag is used that has a tuning frequency outside the range over which communication is possible for the interrogator, there is a problem in that trimming of the antenna pattern is required, thereby increasing the cost due to an increase in the number of processes.
Furthermore, in the device of Japanese Unexamined Patent Application Publication No. 2005-345802, the electronic equipment initiates normal operation even with a unit of an inferior imitation product if the identification code of the RFID tag matches, whereby the electronic equipment main body may be damaged. Even if the identification code of the RFID tag of the removable unit is encrypted, the encryption algorithm and the encryption key can be determined by analyzing the IC, and thus, duplication/fabrication of the RFID is possible. Therefore, although the authentication determination using RFID tags may be effective to prevent improper use, since encryption can be analyzed easily in an environment in which proper consumable items as well as electronic equipment main bodies are sold together, it is difficult to fully prevent improper use.